Accident Analysis and Prevention 71 (2014) 15–21 Contents lists available at ScienceDirect Accident Analysis and Prevention jo u r n al homepage: www.elsevier.com/locate/aap Effects of excessive speeding and falling asleep while driving on crash injury severity in Ethiopia: A generalized ordered logit model analysis Teferi Abegaz a,∗ , Yemane Berhane b , Alemayehu Worku c , Abebe Assrat d , Abebayehu Assefa e a School of Public and Environmental Health, College of Medicine and Health Sciences, Hawassa University, Hawassa, Ethiopia b Addis Continental Institute of Public Health, Addis Ababa, Ethiopia c School of Public Health, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia d Ministry of Transport, Addis Ababa, Ethiopia e World Health Organization (WHO) Ethiopia, Addis Ababa, Ethiopia a r t i c l e i n f o Article history: Received 8 December 2013 Received in revised form 3 May 2014 Accepted 3 May 2014 Keywords: Injury severity Generalized ordered logit model Significant factors Highway safety a b s t r a c t The severity of injury from vehicle crash is a result of a complex interaction of factors related to drivers’ behavior, vehicle characteristics, road geometric and environmental conditions. Knowing to what extent each factor contributes to the severity of an injury is very important. The objective of the study was to assess factors that contribute to crash injury severity in Ethiopia. Data was collected from June 2012 to July 2013 on one of the main and busiest highway of Ethiopia, which extends from the capital Addis Ababa to Hawassa. During the study period a total of 819 road crashes was recorded and investigated by trained crash detectors. A generalized ordered logit/partial proportional odds model was used to examine factors that might influence the severity of crash injury. Model estimation result suggested that, alcohol use (Coef. = 0.5565; p-value = 0.017), falling asleep while driving (Coef. = 1.3102; p-value = 0.000), driving at night time in the absence of street light (Coef. = 0.3920; p-value = 0.033), rainfall (Coef. = 0.9164; p- value = 0.000) and being a minibus or vans (Coef. = 0.5065; p-value = 0.013) were found to be increased crash injury severity. On the other hand, speeding was identified to have varying coefficients for different injury levels, its highest effects on sever and fatal crashes. In this study risky driving behaviors (speeding, alcohol use and sleep/fatigue) were a powerful predictor of crash injury severity. Therefore, better driver licensing and road safety awareness campaign complimented with strict police enforcement can play a pivotal role to improve road safety. Further effort needed as well to monitor speed control strategies like; using the radar control and physical speed restraint measures (i.e., rumble strips). © 2014 Published by Elsevier Ltd. 1. Introduction Severity of an injury is the result of a complex interaction between several factors representing driver and other road users, road characteristics, vehicle defect and design, and environmen- tal characteristics including weather condition and light (Mondal et al., 2011; Thompson et al., 2013). Understanding to what extent each factor contributes to the severity of crash related injury is one of the most effective means to improve highway safety. The human factor appears in the literature as being the most common determinants of road safety. Demographic characteristics: ∗ Corresponding author. Tel.: +251 911361607. E-mail addresses: teferiabegaz@gmail.com, tefabeg@yahoo.com (T. Abegaz), yemaneberhane@gmail.com (Y. Berhane), alemayehuwy@yahoo.com (A. Worku), abebeasrt@yahoo.com (A. Assrat), abebayehua@et.afro.who.int (A. Assefa). male, younger and older drivers are more likely to be involved in death and severe injury crashes (Dissanayake and Lu, 2002; Helai et al., 2008; Shope and Bingham, 2008; Haleem and Gan, 2013). As indicated by many researchers the strongest association of crash injury severity are related to behavioral factors, including: alcohol/drug use (Kuruc et al., 2009; Tsui et al., 2010; Ponce et al., 2011; Hels et al., 2013); speeding (Dissanayake and Lu, 2002; Afukaar, 2003); failure to wear seat belts (Munk et al., 2008; Siskinda et al., 2011; Kashani et al., 2012); using mobile phone while driving (Violanti, 1998) and sleep/fatigue (Radun and Summala, 2004). Speeding is a critical safety concern, especially for developing countries, where fatalities are more common among pedestrians and users of two- and three-wheelers (Mohan, 2002). Fatigue crashes are usually severe, as the driver makes no attempt to limit the consequence (Radun and Summala, 2004). Such types of crashes are linked with the nature of the road alignment; good condition of the road network make the driver task easy and http://dx.doi.org/10.1016/j.aap.2014.05.003 0001-4575/© 2014 Published by Elsevier Ltd.